Ink Content Research Articles

Design of printing ink spectral collection system and research on ink proportion prediction method

In spectral-based ink content measurement, improving the accuracy of the spectral collection system and reducing the algorithm complexity of the ink content measurement model are important aspects of research. This study designs a spectral collection system with an M-type Czerny–Turner optical path structure, uses a third-order polynomial fitting method for calibration analysis, collects the spectral of the standard color card and denoises it through Savitzky–Golay convolution smoothing, and establishes a functional relationship between the spectral and the logarithm of ink content. Uninformative Variable Elimination (UVE) and Competitive Adaptive Reweighting Sampling are used to perform comparative analysis on feature wavelength extraction, and a prediction model for printing ink content is established. Experimental results show that the R2 of ink C, ink M, and ink Y are 0.9981, 0.9975, and 0.9892, respectively, and the root mean square error is 0.0134, 0.0153, and 0.0317, respectively, showing good performance in ink prediction accuracy.

Porous Thin Films with Large Specific Surface Area on the Basis of Spray-Coated Metal Aerogels

The preparation of aerogels in the form of thin films deposited on a substrate (e.g., as an electrode material) is an attractive but challenging task. Such thin films are expected to combine the highly porous gel nanostructure, good mechanical stability, and a remarkably high specific surface area with efficient charge-carrier transport via the interconnected nanoparticle chains. All together, they make them attractive for the fabrication of (electro)catalysts or sensors for microfluidics, flexible electrodes for microelectronics, soft electrodes compatible with a stress-sensitive bioenvironment, etc. In this work, thin aerogel films of colloidal Pd and PtNi building blocks were prepared from the corresponding wet gels using a spray technique. The films were fabricated on substrates of around 1.5 cm2. During the modification of the substrates, the film thickness can be adjusted by controlling the ink content (flow rate, gas pressure, and temperature) and the number of spray cycles. In this way, both the electrical (down to Rs = ∼0.2 kOhm/sq) and optical parameters of the thin porous films can be tuned. Comparative studies of the pore and surface structures of the films have confirmed their integrity and the highly porous structure typical for aerogels. In perspective, spray-coated aerogels can be easily adapted to industrial applications because upscaling is possible and expensive equipment such as supercritical or freeze-dryers is not required. It is important to note that the spray-coating technique is applicable through a mask or can be converted to inkjet printing, which allows for the desired micropatterning of aerogel thin films.

Ultrasound pretreatment and enzymatic deinking by using bacterial cellulases from rice husk

Ultrasonic pretreatment could improve the accessibility of enzymes to cellulosic fibers, hence expanding the access of enzymes to effectively remove ink from paper. In this study, enzymes were isolated from paddy rice husks and utilized for biodeinking process. The characterizations of deinking from the pulp filtrate and paper samples were carried out to understand the effect of bacterial cellulases and ultrasonic pretreatment with time variables. The results showed that cellulases from bacterial isolates had the ability to hydrolyze cellulose at 1.78 U/mL enzyme activity. Ink content measurement showed 2310 ppm of ink was removed in the paper samples with 15 min of ultrasound pretreatment and 2% cellulases. Meanwhile, morphological analysis showed significant differences in the surface areas between treated and untreated paper samples. The highest crystallinity index achieved was 70.9%, and thermal resistance was 21.0%. Other paper qualities such as stain decrease, and brightness level improvement were observed. The combination of 2% cellulases with optimum ultrasonication duration resulted in exceptional wastepaper recycling process.

Fractal algorithms and RGB image processing in scribal and ink identification on an 1819 secret initiation manuscript to the “Philike Hetaereia”

Historical texts incorporate important characteristics that need to be assessed including genre, text structure and content. Often overlooked are characteristics of handwritten manuscripts commonly divided into legibility, readability and aesthetics. To determine the scientific feasibility of classification of handwritten texts an objective approach is developed to describe twenty handwritten pages of an 1819 Greek manuscript, that refers to the initiation to the Greek secret “friendly society” (Philike Hetaereia) organization, established as part of the Greek independence against the Ottoman Turks. It is investigated through a fractal and RGB image analysis approach. Fractal Minkowski Dimension was applied on the handwritten text and the RGB color analysis on the ink and paper and both were used as a non-invasive manner and revealed interesting results. The novel RGB image analysis and the fractal analysis of the manuscript identified respectively, five iron gall inks and four scribes from the ink content and handwritten styles, of the compact five lines text and whole text pages. The novel approach was verified with another old manuscript of known ink pigments, as well as with thirteen known handwritten texts of that period and four prints representing modern and similar period texts substantiating the findings of the novel methods.

Plasma jet printing of metallic patterns in zero gravity

Printing of metallic, semiconducting and other materials is a key step in printed and flexible electronics. Plasma jet printing is emerging as an alternative to inkjet, aerosol and other competing printing techniques since it is a single step process that does not require post-thermal annealing to obtain consolidated printed films with good adhesion. Here, we provide results for printing metallic films and patterns from flight tests with varying gravity from 0 to 2 G. The conductivity of the as-printed silver film without any post-sintering was 12% of the bulk value for silver. As expected, the absence of gravity has no adverse impact on the print quality since the ink content along with the plasma is forcefully ejected by the applied electric field towards the substrate, while the successful flight test itself attests to the robustness of the printer and the printing technique.

Research on Measurement Method of Two-Color Mixed Ink Content Based on Spectrum

Research on Measurement Method of Two-Color Mixed Ink Content Based on Spectrum

Research on the measurement method of printing ink content based on spectrum

In the printing quality inspection, measuring the primary color ink content of printed products is an important link. In order to obtain accurate measurement results in the ink content measurement system, this study preprocesses the interference information such as stray light and noise in the collected ink content spectrum information of cyan, magenta, and yellow samples firstly. Considering the limited denoising ability of common filtering methods in the frequency domain, a composite filtering method combining median filtering and wavelet transform is introduced to preprocess the collected spectral signal. The system not only suppressed the random interference, but restored original signal well. Then, considering that there are many redundant data in full-wavelength spectral reflectance data, the Successive Projections Algorithm (SPA) and Competitive Adaptive Reweighted Sampling (CARS) algorithm were used to extract characteristic wavelengths from the preprocessed information. After extracting the characteristic wavelengths, the primary color ink content prediction models were built based on the Partial Least Squares Regression (PLSR) and Support Vector Regression (SVR) algorithms. The test results show that SVR models based on SPA and CRAS feature extraction algorithms have better prediction effect than PLSR models. Among them, CARS-SVR algorithm models have the best prediction effect, and the modeling wavelengths of three primary color samples decreases by 82.75%, 69.25% and 90.50%, compared with the whole wavelengths. The Cross-Validation Root Mean Square Error (RMSECV) and coefficient of determination (R2) of CARS-SVR content prediction models are 0.0256, 0.0182, 0.0249 and 0.9931, 0.9966, 0.9936, respectively. The system showed better measurement accuracy.

Environmental impact of printing inks and printing process

In the Printing Industry, printing inks, varnishes, lacquers, moistening solutions and washing solvents (ethanol, methyl acetate, ethyl acetate, isopropanol, n-propanol, hexane, benzene, toluene, xylene, isopropyl acetate, propyl acetate, dimethyl ketone, glycols and glycol ethers) contain volatile organic compounds (VOCs) and air pollutants (HAPs). Especially solvent based inks used for flexo, gravure and screen printing, offset printing dampening solutions and cleaning solvents contain high concentration of VOC. These organic compounds evaporate during the production process or contribute to the photochemical reaction. VOCs and HAPs, together with sunlight and nitrogen oxides, cause photochemical smoke, air particles and ground level ozone emission in the atmosphere. The VOCs and heavy metals can lead to soil and even water pollution when left in landfill. The amount of solvent retained by flexo, gravure and screen-printed products is 3-4% of total ink solvent used. The solvent in the printed ink content, except for the one held by the printed material evaporates in its own environment after the printing process. Most of these solvents and organic compounds used in printing environment contain at least one carbon and hydrogen atom and have negative effects on health and environment.In this study, the environmental impacts and risks of inks and solvents used in the printing industry have been evaluated. Measures to be taken to reduce and manage these environmental effects and risks have been addressed and recommendations have been made.

Multi-Technique Characterization of Gas Diffusion Fuel Cell Electrodes

The development of large-scale manufacturing capabilities for the most critical component in polymer electrolyte membrane fuel cells (PEMFC), the membrane electrode assembly (MEA) is essential for the commercialization of this technology. Most commonly, the catalyst is combined with a solvent to make an ink, which is then deposited onto the polymer membrane, producing a catalyst coated membrane (CCM). Gas diffusion electrodes (GDEs), in which the catalyst layer (CL) is deposited directly on the gas diffusion media (GDM) are easier to manufacture in a roll-to-roll (R2R) fashion. Additionally, some of the issues associated with polymer electrolyte membrane swelling that are observed during CCM fabrication are eliminated with R2R GDEs. While significant work has been done to study the differences in initial performance for CCM based MEAs further studies are needed on electrodes made with scalable routes.This work focuses on comparing several spectroscopic characterization methods that were applied to a set of GDEs to better understand the bulk and local ionomer distribution and its correlation to initial performance metrics. The GDEs were made with a state-of-the-art Pt catalyst supported on high surface area carbon, a 0.9 ionomer to carbon ratio, and a 1-propanol and water ink solvent mixture. The GDEs in this study were fabricated by an ultrasonic spraying system, as well as, by slot die and gravure roll-to-roll coating methods. Various ink solvent ratios were used, and in the case of the sprayed electrodes the incorporation of additional ionomer on the GDE surface was explored. The F/Pt ratio of all the GDEs was measured by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) probing the difference in the ionomer amount at different depth (around 10 vs 100 nm). Additionally, scanning transmission electron microscopy (STEM-EDS) analysis of the electrode cross-sections was performed at low magnifications to measure F/Pt ratio within the entire thickness of the electrode as well as at a higher magnification to probe the local F/Pt ratio inside of the catalyst layer (CL). The F/Pt from the three techniques was then correlated with the initial performance metrics of potential at 1 A/cm2 and at 1.5 A/cm2, as well as, CL resistance, and electrochemically active surface area (ECSA). It was found that values extracted from both SEM-EDS and XPS show similar correlations that track with the initial performance values. The R2R slot die GDE with a high water ink content showed the highest F/Pt at the surface of the electrode and demonstrated the best performance. A certain range of ionomer content present at the electrode surface was shown to induce a more favorable Cl/membrane interface improving the fuel cell performance. This work highlights the importance of assessing the composition and structure of fuel cell electrodes at different surface depths and builds towards identifying key metrics that correlate to performance that can be derived quickly to explore a larger space of processing and fabrication parameters.

Tailoring electrode microstructure via ink content to enable improved rated power performance for platinum cobalt/high surface area carbon based polymer electrolyte fuel cells

Improvements in polymer electrolyte fuel cell (PEFC) electrode performance have primarily focused on catalyst and ionomer developments, marginalizing the importance of catalyst ink formulation. Herein, the effect of ink formulation is examined across a series of cathodes comprised of PtCo supported on high surface area carbon (PtCo/HSC) and Nafion ionomer using an array of in situ electrochemical and ex situ characterization techniques. In contrast to prior work on Pt/Vu systems, ink water content had little effect on the electrochemically determined ionomer coverage for the PtCo/HSC electrocatalyst examined here. Characterization using nano-scale resolution X-ray computed tomography (nano-CT) demonstrated that water-rich ink formulations lead to a reduction in aggregate size (ionomer + PtCo/HSC), improving local O2 transport. This understanding, combined with the use of a commercially-available electrocatalyst was used to produced state-of-the-art membrane electrode assemblies with Pt loadings of 0.03/0.08 mgPt/cm2 on the anode and cathode respectively, having; i) > 1 A/mgPt (0.9 ViR-free, 150 kPa, 80 °C, 100% RH, H2/O2), ii) 320 mA/cm2 at 0.8 V, 150 kPa, 80 °C, 100% RH, H2/Air), and iii) > 1 W/cm2elec at rated power (0.67 V, 250 kPa, 94 °C, 65% RH, H2/Air) or < 0.11 gPt/kWrated.

Development of detached root and leaf assays to evaluate the antagonistic properties of biocontrol agents against Fusarium wilt of banana

The failure of bio-control agents (BCAs) in suppressing Fusarium oxysporum f. sp. cubense tropical race 4 (Foc-TR4) was reported in vivo although antagonism was obtained from in vitro dual culture assay. This study aims to develop rapid assays to validate the antagonism of BCAs using detached banana leaves and roots. Both Trichoderma harzianum and Pseudomonas aeruginosa reduced root lesion length (2.7–3.1 cm) compared to 4.9 cm in TR4 treatment. BCA-treated leaves reduced wilting severity from 93.75 to 33.75%. Trypan blue staining showed lower cell death area in BCA-treated roots and leaves. Reduced leaf wilting was indicated by lower red ink content and higher chlorophyll content in BCA-treated leaves. Both defense-related genes, PR-1 and PR-3 were expressed in BCA-treated roots and leaves which could be associated with reduced root necrosis and leave wilting. In conclusion, both assays could be served as rapid methods to select potential BCAs before attempting large-scale trials.

Printing pharmaceuticals by inkjet technology: Proof of concept for stand-alone and continuous in-line printing on orodispersible films

Orodispersible films (ODFs) are promising dosage forms for special patient populations like paediatrics or elderly persons. By printing active pharmaceutical ingredients (APIs) onto orodispersible films, the flexibility of drug dosing is increased and therefore provides potential for personalized medicines. Until now, only small-scale experiments have been conducted, where continuous jetting was performed,but no continuous ODF production was realized. This study deals with the technology transfer from a small-scale inkjet printing system to a pilotscale process by incorporating the same print head assembly into a continuous ODF production process. ODFs made from hydroxypropylcellulose were non-continuously printed multiple times with test ink containing a blue colorant as model drug and were compared to continuously printed ODFs. To identify optimal manufacturing conditions, parameter settings like firing frequencies, resolution, voltage, etc. were varied and these effects were analysed by UV–Vis spectroscopy, image analysis and light microscopy. During continuous production, a linear correlation between firing frequency (100 to 600 Hz) and deposited colourant content could be observed (R = 0.999) as well as for the applied voltage (90–110 V) and the ink content (R = 0.998). A minor impact of the distance between the print head and the substrate was observed. By increasing the natural resolution (50 dpi) of the print head, the deposited ink amount could be doubled. A transfer from the non-continuous production (1 layer of 1 cm × 2 cm with a resolution of 750 dpi × 750 dpi) to the continuous production (corresponding to 380 Hz firing frequency on 6 cm2 ODF) was successfully performed. Furthermore, image analysis was proven as useful tool for process analytical technology (PAT) of the continuously printed ODFs. The continuous ODF production with direct printing enabled various printing concepts, which may serve for individualized dosing in personalized medicine treatment in the near future.

Deinking process water flotation: An innovative solution to improve deinking and papermaking processes efficiency

High and uncontrolled surface active substances (SAS) concentrations in deinking line process waters strongly disturb flotation deinking. Indeed, their adsorption at air/water and ink/water interfaces stabilizes air bubbles and ink particles, reducing ink collection during flotation. In addition, foam stabilization promoted by SAS reduces froth drainage and consequently enhances suspended solids losses. All in all, selectivity of flotation is negatively affected by excessive SAS concentrations. Floating process water with adapted technology, a patented solution, is an efficient way to decrease SAS concentration and thereby recover flotation deinking selectivity. This concept was tested at industrial scale with success. First loop clear filtrates of a deinked pulp line (for newsprint production) were floated. At steady state, this treatment allows a 20% reduction of the SAS concentration in first loop process water. Evaluation of ink removal selectivity at pre-flotation and post-flotation showed a significant improvement in comparison with reference values. During the trial, the mill could either produce pulp with lower ink content and consequently higher brightness (50 ppm effective residual ink concentration [ERIC] less, corresponding to a 1 brightness point increase) for similar losses, or similar pulp quality with 1% to 2% yield improvement, representing a huge cost reduction. In addition, beneficial side effects were reported, such as reduced deinking chemicals consumption (soda, silicate, and bleaching agents) and better paper machine runnability, especially in terms of stickies breaks.

Fractionation by micro-hole pressure screening and hydrocyclone applied to deinking line rationalization and future manufacturing concept

This study pursued two objectives related to deinking. The first objective deals with the application of fractionation for deinking operations rationalization, which requires all free ink separation in one fraction and treatment in ink removal operations. Following accomplishment of the first objective, the second objective was fractions generation for stratified sheet formation. The first objective requires separation based on length, and the second requires separation by development of surface characteristics. The experimental plan was focused on selective fines separation and further valorization of fiber and fines fractions. It was shown that fractionation by a pressure screening system equipped with a smooth hole basket with 0.25mm perforations was very selective towards fines (free ink, fillers, cellulosic fines) separation in the accepts. Long fibers, as well as specks, were retained in the rejects fraction. Due to the higher selectivity of the micro-hole screen, fibers are retained on the screen basket. Hence, they are not subjected to flotation operations, thereby effectively reducing their probability of being lost during flotation. This essentially translated into a fractionation-deinking concept. It was also shown that 1-stage micro-hole fractionation and fines flotation provided higher yield than conventional direct pulp flotation, though the final residual ink content was high. A multistage fractionation process would allow further reduction in long fiber residual ink. The second objective was achieved by applying hydrocyclone fractionation on the fine and fiber fractions generated.Separation was based on fiber and fines development. This new fractionation strategy allowed production and characterization of four different fractions: well developed fibers/coarse fibers and fibrillar/flake type fines.

Pilot-scale development of cavitation-jet deinking

A new deinking method for paper recycling using a fluid-jet cavitation technique has been developed. An in-house, laboratory-scale device revealed that cavitation-jet treatment without deinking chemicals decreases ink and dirt content in deinked pulp. As the next step, a pilot-scale deinking device, 10 times larger than the laboratory device, was designed. The specifications of the pilot device were determined by experiments using the laboratory device. The pilot device was installed in a deinked pulp mill, and the effects of multijet nozzles within a reacting vessel, depending on consistencies of the deinked pulp, were investigated. The operation stability of the device was examined as well. The shape and size of an effective cavitation zone for ink detachment were changed by nozzle diameter and upstream pressure of the jet. The results from batch cavitation treatment of deinked pulp revealed that the device could treat the pulp with consistency up to 3.8% by weight and decrease attached ink, dirt specks, and macrostickies without addition of deinking chemicals. Hydrophobic colloidal materials, including microstickies after cavitation treatment, became more difficult to attach to hydrophobic surfaces. Continuous cavitation treatment gave similar results to those from batch treatment. Two types of multiple nozzle arrangements, parallel and cross-nozzle modes, decreased dirt specks to the same level as a mill disperser. On the other hand, the reductions of macrostickies by those modes were higher than with the disperser. Because treatment consistency increased more than 3%, treatment efficiency and device performance were significantly improved. This could be a big step toward practical use of cavitation treatment.

The Improvement of Recycled Newsprint Properties by In-situ CaCO3 Loading

In-situ CaCO3 loading of old newspaper (ONP) fiber furnish was studied as a method to improve the properties of recycled newsprint paper. The effects of in-situ loading on the morphological and physical properties of ONP furnish were examined comparatively with conventional loading methods (addition of ground or precipitated CaCO3, without and with pre-flocculation treatment). The effective residual ink content (ERIC) and macro sticky content began to decrease as soon as the in-situ CaCO3 formation started by the injection of carbon dioxide to the reaction tank, where the ONP furnish and calcium oxide mixture was agitated in high shear. When the reaction finished at pH 7, there were no more decreases of ERIC value and sticky content. Improvement of first pass retention and brightness was significant for the in-situ CaCO3 loading method. The decrease in breaking length with the addition of CaCO3 in the in-situ formation method was equivalent to or slightly lower than that of the CaCO3 pre-flocculation method, which is a method well known to give higher strength properties. Optical images from the FlowCAM® dynamic imaging particle analyzer showed strongly attached organic (fines) and inorganic (CaCO3) materials in the in-situ CaCO3 loading method.

Effect of wavelength selection on determination of ink content and ink elimination at 700 or 950 nm

Effective residual ink concentration (ERIC) and ink elimination (IE) are often used to evaluate the removal of printing ink in deinking. For these measurements, the light reflectance is recorded at 950 nm or 700 nm even though only the use of the former for effective residual ink concentration is instructed in the ISO and TAPPI standards. In this study, these two wavelengths were compared using a set of recycled pulp samples having variable fiber fines, fillers, and ink contents. It was seen that both wavelengths are well suited for the determination of effective residual ink concentration, especially when the recovered papers are not green or blue. Effective residual ink concentration values measured at 700 nm are higher than those obtained with 950 nm because, in addition to black printing ink, the presence of cyan-colored inks contributes to the former. Ink elimination values are similar for both wavelengths because ink elimination is a percentage ratio of ink removal in flotation. The fine materials and printing ink also affect light scattering at 950 nm, although the range appears narrower for 950 nm than for 700 nm.

Ink and dirt behavior in pulping after artificial aging of cold-set offset printed newspapers in different humidity conditions

Although moisture has a decisive role in the permanence of cellulose and unprinted paper, its role in ink release from the surface of printed recovered papers remains unclear. This work aimed to determine whether various relative humidity levels in the artificial aging test affect ink release from the surface of the paper and its fibers when pulping cold-set offset printed newspapers in alkaline pulping conditions. The results showed that relative humidity variations from 30% to 70% negligibly affected ink release at 60°C. However, compared with these lower humidity levels, exposure to 90% relative humidity for at least 25h resulted in a higher ink content bound to fibers, a greater formation of visible dirt specks after pulping and a smaller formation of microscopic ink particles. In practical applications, the accurate estimation of climate effects during the storage and the transportation of recycled papers requires that humidity conditions are taken into account while performing artificial aging tests with paper products.

Optical analysis of ink and other contaminants in process waters

Analysis methods developed specifically to determine the presence of ink and other optically active components in paper machine white waters or other process effluents are not available. It is generally more interest¬ing to quantify the effect of circulation water contaminants on end products. This study compares optical techniques to quantify the dirt in process water by two methods for test media preparation and measurement: direct process water filtration on a membrane foil and low-grammage sheet formation. The results show that ink content values obtained from various analyses cannot be directly compared because of fundamental issues involving test media preparation and the varied methodologies used to formulate the results, which may be based on different sets of assumptions. The use of brightness, luminosity, and reflectance and the role of scattering measurements as a part of ink content analysis are discussed, along with fine materials retention and measurement media selection. The study concludes with practical tips for case-dependent measurement methodology selection.

Xylanase Isozymes from the Newly Isolated Bacillus sp. CKBx1D and Optimization of Its Deinking Potentiality

Recycling of civic paper waste by enzyme-based technology is nowadays a point of much concern for pollution-less green environment. In this study, the deinking effectiveness of purified xylanase from a newly isolated bacterium was evaluated for recycling of laser jet paper waste. A potent xylanases-producing bacterium from the microbial consortia of termite gut was isolated, which was further identified on the basis of 16S rRNA sequence as Bacillus sp. CKBx1D. In submerged fermentation condition, the isolate produced the highest level of xylanase (480U/ml) at 36h of growth. The extracellular xylanase system comprises of three distinct isozymes (est. Mw 35.28, 28.63, 18.94kDa). The deinking of laser printed paper waste was performed using the purified enzyme mixture. Whole operational parameters were optimized using the Response Surface Methodology; it was found that at pH 6.8 with 47.2h of continuous shaking at constant temperature of 35°C, enzymes showed best deinking activity. After enzyme treatment, the physical properties of the pulp like brightness and ERIC (effective residual ink content) values were enhanced, whereas the pulp opacity was more reduced than the control treatment. Hence, the bacterial isolate and its xylanolytic enzyme system could efficiently be used in recycling paper waste as deinking agent.